Dorin,

>>You can open another file with low level function FOPEN({file},1). If the file is already opened by another app, then FOPEN() returns -1 and FERROR() returns 5 (Acces denied) .

That solution implies that your application starts, creates the file, and eventually exits normally erasing the file. But what happens if your application crashes or there is some other irregular exit? I think checking for a window with your application's caption is probably more reliable.

David